I'll rephrase: 5 points that Lord Frey will accept. I included Theon who might not agree or be accepted. It is just as possible that Frey will not agree to a deal of only a squire and wards in addition to a bethrothel, and request changes, even if only for a different 5 points.Because it said so on the update? 5 Point require to pass. Giving too much to the Frey might make them happy but it would also make Robb look like a bad negotiator from the North lords' point of view. The Freys haven't done anything but we're piling them with good things.
If you want to offer just the minimum and hope it passes, then that is perfectly valid. I prefer to maximize our potential gains via chance of inheritance of the Twins and hopefully nudging Theon into staying in our camp.